Crystallography, magnetic susceptibility, heat capacity, and electrical resistivity of heavy fermion LiV$_2$O$_4$ single crystals grown using a self-flux technique

TL;DR

This study reports the growth of high-quality LiV₂O₄ single crystals using a self-flux method and investigates their magnetic, thermal, and electrical properties to understand heavy fermion behavior and the effects of magnetic defects.

Contribution

It introduces a flux growth technique for LiV₂O₄ single crystals and provides initial measurements revealing the impact of magnetic defects on their properties.

Findings

Magnetic defects cause Curie-like upturns in susceptibility.

Annealing reduces magnetic defect concentrations.

High specific heat coefficient observed at low temperatures.

Abstract

Magnetically pure spinel compound ${\rm LiV_2O_4}$ is a rare $d$-electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy fermion behavior in the pure material. In addition, it is known that small concentrations ($< 1$ mol%) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report flux growth of ${\rm LiV_2O_4}$ and preliminary measurements to help resolve these questions. The magnetic susceptibility of some as-grown crystals show a Curie-like upturn at low temperatures, showing the presence of magnetic defects within the spinel structure. The magnetic defects could be removed in some of the crystals by annealing them at 700 $^\circ$C\@. A very high specific heat coefficient $\gamma$ = 450 mJ/(mol K${^2}$\@) was obtained at a temperature of 1.8 K for a crystal containing a magnetic defect concentration $n$${\rm_{defect}}$ = 0.5 mol%. A crystal with $n$${\rm _{defect}}$ = 0.01 mol% showed a residual resistivity ratio of 50.